In the writers' first draft script of "Dear Doctor", the Pyrithian bat that Phlox kept as a pet was a male rather than a female. When Hoshi Sato arrived in his sickbay (at the start of the episode's first act), Phlox told her that she had just missed her chance to feed the creature (whose species name was misspelled "Pirythian bat"). Sato readily accepted this news, telling Phlox that the last time she had fed the animal, it had become "a little jumpy" around her. However, Phlox reminded her the animal only bit males. Nonetheless, Sato was skeptical the creature could tell the difference between the genders of whoever fed it.

In the final draft script of "A Night in Sickbay", the Pyrithian bat was described as "large" and "dark blue."

In ultimately omitted dialogue from the final draft script of "Damage", Phlox mentioned to T'Pol that his Pyrithian bat was in heat and that, as a result, it very often made a "cooing" noise that Phlox described as "incessant" and "trying."